Natural Variation in Volatile Emissions of the Invasive Weed Calluna vulgaris in New Zealand

Abstract

Invasive plants pose a threat to natural ecosystems, changing the community composition and ecological dynamics. One aspect that has received little attention is the production and emission of volatile organic compounds (VOCs) by invasive plants. Investigating VOCs is important because they are involved in vital ecological interactions such as pollination, herbivory and plant competition. Heather, Calluna vulgaris, is a major invasive weed in New Zealand, especially on the Central Plateau, where it has spread rapidly since its introduction in 1912, outcompeting native species. However, the chemical behaviour of heather in its invaded ranges is poorly understood. We aimed to explore the natural variation in volatile emissions of heather and the biotic and abiotic factors influencing them on the Central Plateau of New Zealand. To this end, foliar volatiles produced by heather at four different sites were collected and analysed using gas chromatography coupled to mass spectrometry. Soil properties, herbivory and other environmental data were also collected at each site to investigate their effects on VOC emissions using generalised linear models (GLMs). Our results reveal significant differences in VOC emissions between sites and suggest that soil nutrients are the main factor accounting for these differences. Herbivory and temperature had only a minor effect, while soil water content had no impact. Further studies are needed to investigate how these variations in the invasive plant’s foliar volatiles influence native species.

Seasonal and environmental variation in volatile emissions of the New Zealand native plant Leptospermum scoparium in weed-invaded and non-invaded sites

“…Dried soil from each site was then homogenised to represent the average for respective sites and used for nutrient analyses. Soil pH, total carbon (C), total nitrogen (N), potassium (K), calcium (Ca), magnesium (Mg) and sodium (Na), and soil temperature were measured as described in 16 .…”

“…In the field, the Mediterranean plant Rosmarinus officinalis also reduced its emission of monoterpenes when neighbored with Pinus halepensis 61 . A recent study also showed that the invasive plant Calluna vulgaris produces lower levels of volatiles at a site where it co-exists with another invasive plant Cytisus scoparius, which is a nitrogen-fixer, capable of modifying soil properties 16 . However, other studies also show lower emissions when plants were paired with conspecifics 62 .…”

“…S1). This may indicate a disruption in communication between mānuka and its principal herbivore and suggests that the abundance of herbivorous arthropod is reduced at sites where invasive plants are dominant 16,45 .…”

Volatile Profiling of Fifteen Willow Species and Hybrids and Their Responses to Giant Willow Aphid Infestation

“…VOCs from willow branches were collected using the push-pull headspace sampling method as described in Effah, et al [48]. Among the twelve plants in the row plots of each species or hybrid, one of the middle ramets (plants 5, 6 or 7) per plot was chosen to ensure that the VOCs collected were released from that treatment, without receiving VOCs from different neighboring plants, for a total of six plants per species.…”

Herbivory and Attenuated UV Radiation Affect Volatile Emissions of the Invasive Weed Calluna vulgaris

“…The impacts of biotic and abiotic stressors on VOC emissions have been poorly studied in plant invasion scenarios and, to our knowledge, only two studies have explored the effects of environmental variables on VOC emission by invasive plants [20,21]. Under controlled conditions, elevated CO 2 levels caused increased emissions of β-caryophyllene in the invasive weed Mikania micrantha [20], while poor soil fertility accounted for lower VOCs emission by the invasive Calluna vulgaris in the field [21]. More of these studies are needed to enhance our understanding of the mechanisms behind plant invasion, and the potential effects of an invasive plants' volatile compounds on the native flora, fauna and microbiota.…”